Comments

I really liked the article on micromorts in Plus and agree that it is a great way of comparing risks as an approximation. However I'm sure that most people don't view the risks of undertaking activities to be like buying a lottery ticket (but perhaps I'm wrong). Many of the activities you list, such as cycling, horse-riding, scuba-diving, or skiing, are activities where a degree of skill, competence or mastery of technique is required. By practising most individuals gain in competence and thus at least gain the perception that they are more in control of their destiny i.e. they think they can change the value of their lottery ticket. There is some evidence for this, for example an analysis of skiers shows that those in their first weeks of the activity are at highest risk of serious injury, this risk then declines but then later it starts to rise again after several months of activity. This later rise in risks appears to be associated with greater skill levels which are then associated with more adventurous skiing (e.g. off-piste skiing). In some ways this is not so dissimilar to your idea of smoking where you don't get to throw away your lottery ticket and start again each time you take part in the activity. However unlike smoking, a degree of competence may improve your risks, but greater competence may lead to over confidence and a worsening of your risks.
Reader in Therapeutic and Molecular Immunology
Department of Pathology
Tennis Court Road
Cambridge CB2 1QP http://www.path.cam.ac.uk/~mrc7/